Printers, projection televisions and the like require a light source with three colors R (Red), G (Green) and B (Blue) as their light sources. As the light source, a wavelength converting laser device has been developed which generates second harmonics (SHG: Second Harmonic Generation) of fundamental waves of 900 nm band, 1 μm band and 1.3 μm band laser light rays by using a nonlinear material. To achieve high conversion efficiency from the fundamental waves to the second harmonics, it is necessary to increase the power density of the fundamental waves on the nonlinear material and to obtain laser light rays with high light focusing power with a small wavefront aberration.
Thus, conventionally, an array type wavelength converting laser device as shown in FIG. 10 which can implement multiple oscillations in a spatial mode has been proposed (see Patent Document 1, for example). The array type wavelength converting laser device is comprised of a semiconductor laser 1001 with a plurality of light emitting points for outputting pumping light in a one-dimensional form; a planar waveguide type laser element 1002 with a heat sink (not shown) joined thereto for generating fundamental waves while being excited by the pumping light; a wavelength converting element 1003 for carrying out wavelength conversion of the fundamental waves to output second harmonics; and an output mirror 1004 for reflecting the fundamental waves and transmitting the second harmonics. In addition, in FIG. 10, a lens 1005 for focusing the light is placed after the output mirror 1004 of the laser device. Thus, temperature distribution is produced in the laser medium of the planar waveguide type laser element 1002 by the heat sink, thereby creating refractive index distribution in the laser medium. The laser medium creates a thermal lens effect with an effect equal to aligning a plurality of lenses in the array direction owing to the refractive index distribution in the laser medium. The thermal lens effect can bring about multiple oscillations in a spatial mode, thereby being able to produce the second harmonics with high efficiency.